Cuba condemns Honduras coup as 'criminal, brutal'

* Cuba demands immediate restoration of Zelaya

* Fidel Castro calls coup a "suicidal error"

(Adds comments by Fidel Castro paragraphs 2-4)

HAVANA, June 28 (Reuters) - Cuba condemned Sunday's military coup in Honduras as "criminal, brutal" and demanded the immediate return to office of deposed leftist President Manuel Zelaya.

Former Cuban president Fidel Castro called the coup "a suicidal error" and said there was no room for negotiations with its leaders.

"Their resignation should be demanded and younger officers not beholden to the oligarchy should take over the military," Castro wrote in a column for Cuba's state media.

The army ousted and exiled Zelaya in Central America's first military coup since the Cold War, after his efforts to lift presidential term limits were rejected by his country's Congress, Supreme Court and the military.

"I denounce the criminal, brutal character of this coup," Cuban Foreign Minister Bruno Rodriguez told a news conference in Havana earlier in the day.

Zelaya is viewed by Cuba's communist leadership as a leftist ally and former Cuban leader Fidel Castro had expressed backing for his efforts to hold an unofficial public vote on Sunday to gauge support for his plan to hold a November referendum on allowing presidential re-election.

"This coup has removed a legitimate and constitutional government simply for wanting to hold a vote. There is only one constitutional government in Honduras, and one constitutional president who should return immediately without conditions," Rodriguez said.

The minister denounced what he called the violent treatment of the Cuban and Venezuelan ambassadors by Honduran troops.

Venezuelan President Hugo Chavez said Honduran soldiers took away the Cuban ambassador and left the Venezuelan envoy on the side of a road after beating him during the coup. The Cuban diplomat was later released.

Rodriguez said the Cuban, Venezuelan and Nicaraguan ambassadors had been seeking to give Zelaya's Foreign Minister Patricia Rodas diplomatic protection when Honduran soldiers, their faces hooded, tried to take her away. He said he was extremely concerned for her safety.

Chavez put Venezuela's troops on alert over the coup in Honduras and said he would respond militarily if his envoy to the Central American country was kidnapped or killed.

Rodriguez said there were 84 people, including diplomats, women and children, at the Cuban embassy in Tegucigalpa and said Cuba was "ready to defend the integrity of our embassy". (Reporting by Marc Frank, Editing by Pascal Fletcher)